Assessment of some chlorophyll a fluorescence parameters of different corn cultivars in response to clodinafop-propagrgyl herbicide and salicylic acid

Nowadays, the use of chlorophyll a fluorescence has become a simple and nondestructive method for detecting plant’s photosynthetic response to different kinds of stress. The aim of this research was to evaluate the effects of different concentrations of clodinafop-propagrgyl (TOPIK®) herbicide on some chlorophyll a fluorescence parameters of different corn cultivars (SC260, SC400, SC704) in response to salicylic acid (SA) application (control, seed priming, spraying on plants three days before herbicide treatment, concurrent with herbicide application) in greenhouse of University of Tabriz in 2017, using a factorial arrangement of treatments based on randomized complete block design with three replicates. Results showed that by increasing of TOPIK levels in the absence of SA, the maximum fluorescence (Fm), variable fluorescence (Fv), efficiency and/or activity of water-splitting complex at donor side of photosystem II (Fv/F0) and maximum photochemical efficiency of photosystem II (Fv/Fm) decreased but minimum fluorescence (F0) increased. However, application of SA improved several parameters of chlorophyll a fluorescence in some corn cultivars. Application of SA as seed priming and spraying on plants three days before TOPIK treatment had higher effect on the studied cultivars than SA spraying concurrent with herbicide application. Correlation between the F0 and Fv/F0 was significant and negative. Also shoot dry weight (SDW) taken at 28 days after herbicide application had significant and positive relationship with Fv/Fm taken at 7 days after herbicide application. The findings of this research demonstrates that chlorophyll a fluorescence parameters and especially Fv/Fm are fast and reliable criteria for determining the effects of herbicides, such as TOPIK, and/or plants growth regulators, such as salicylic acid, shortly after treatment as compared to classical methods.